February 4, 20215 yr I only find server boards with 2011-3 sockets or high power boards with X570 AM4 supporting x4x4x4x4 Bifurcation. I mean yes, both have more Lanes, but only für switching an x16 PCIe slot to x4x4x4x4 this is not relevant. Most B550 AM4/1151/1200 boards already switch between two (mechanical) x16 Slots, so they become x8 + x8 on usage. And the Gigabyte W480M even allows x4x4 + x8, but I can't find one, where you can have x4x4 + x4x4 or x4x4x4x4 + none. It would be so nice having much more M.2s without adding an expensive Quad card with controller (30 vs 600 Euro). Did anyone stumble across a B550 AM4/1151/1200 board with x4x4 + x4x4 or x4x4x4x4 support? EDIT: I found this in the specification of the Asus Prime Z590-P. Does it mean it's a general limitation of Intel Consumer CPUs? Quote - Intel® 11th Gen processors support PCIe 4.0 x16 or x8/x8 or x8/x4/x4 modes - Intel® 10th Gen processors support PCIe 3.0 x16 or x8/x8 or x8/x4/x4 modes
February 5, 20215 yr On 2/4/2021 at 10:01 AM, mgutt said: I only find server boards with 2011-3 sockets or high power boards with X570 AM4 supporting x4x4x4x4 Bifurcation. I mean yes, both have more Lanes, but only für switching an x16 PCIe slot to x4x4x4x4 this is not relevant. Most B550 AM4/1151/1200 boards already switch between two (mechanical) x16 Slots, so they become x8 + x8 on usage. And the Gigabyte W480M even allows x4x4 + x8, but I can't find one, where you can have x4x4 + x4x4 or x4x4x4x4 + none. It would be so nice having much more M.2s without adding an expensive Quad card with controller (30 vs 600 Euro). Did anyone stumble across a B550 AM4/1151/1200 board with x4x4 + x4x4 or x4x4x4x4 support? EDIT: I found this in the specification of the Asus Prime Z590-P. Does it mean it's a general limitation of Intel Consumer CPUs? @Intel: I think its by design - Intel CPUs can only handle x16 or x8x8 - The manufacturer determines how the lanes are interconnected by the chipset
February 5, 20215 yr 1 hour ago, Zonediver said: Intel CPUs can only handle x16 or x8x8 Most can also handle 1x8+2x4, that's what I have on one of my servers with a Skylake CPU.
February 5, 20215 yr 7 hours ago, JorgeB said: Most can also handle 1x8+2x4, that's what I have on one of my servers with a Skylake CPU. As far as i know, the 3rd PCIe-Slot is always connected to the chipset (on Mainstream-Platforms) - but maybe a Xeon can handle this different.
February 6, 20215 yr 10 hours ago, Zonediver said: 3rd PCIe-Slot Usually it's not a 3rd slot, it allows to bifurcate a x8 CPU slot as two x4 slots, so for example I have an HBA in one slot and 2 NVMe devices in another, and most CPUs support it, no need for a Xeon.
June 9, 20215 yr Author I found one B550 board with 4x x4 Bifurcation Support: https://dlcdnets.asus.com/pub/ASUS/mb/SocketAM4/ROG_STRIX_B550-E_GAMING/E16546_ROG_STRIX_B550-E_GAMING_UM_WEB.pdf By that this board should support: - 7x NVMe: All x4 (PCIe to M.2 adapter in slot PCIE16_3)
June 10, 20215 yr 23 hours ago, mgutt said: This should allow a ~2000 MB/s array. Possibly, but doubt it, Unraid is not optimized for those speeds, as an example see a read check with 5 NVMe devices (no parity): Single NVMe device was already only about 2.4GB/s, but speed starts decreasing as you add even more.
June 11, 20215 yr Author On 6/10/2021 at 10:27 AM, JorgeB said: Unraid is not optimized for those speeds As you didn't use a parity, I think this was a different bottleneck. Maybe two M.2 NVMe through Intel DMI?
June 11, 20215 yr 1 hour ago, mgutt said: As you didn't use a parity, I think this was a different bottleneck. Maybe two M.2 NVMe through Intel DMI? No, they are all on CPU slots, it's a Xeon e5 v3/v4 board, with 40 PCIe CPU lanes, well 36 usable since 4 go to the onboard NICs.
July 31, 20214 yr On 6/9/2021 at 1:31 AM, mgutt said: I found one B550 board with 4x x4 Bifurcation Support: https://dlcdnets.asus.com/pub/ASUS/mb/SocketAM4/ROG_STRIX_B550-E_GAMING/E16546_ROG_STRIX_B550-E_GAMING_UM_WEB.pdf By that this board should support: - 7x NVMe: All x4 (PCIe to M.2 adapter in slot PCIE16_3) Here's another one. ASRock Rack X470D4U Hope it helps!
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